Speakers
Description
A pilot operation was carried out to mechanically harvest gorse (Ulex europaeus) in Reserva del Saja, Cantabria–Spain, at two selected sites: Ruente and Cruz de Sopeña. The aim was to implement and evaluate a shrub biomass extraction treatment using a single-pass system that cuts, shreds and pneumatically conveys the material into a front-mounted container, while documenting operational performance, costs and harvesting efficiency under contrasting stand conditions.
The harvesting chain consisted of a 200 HP Valtra tractor coupled to a López Garrido TBA 2300 shredder-harvester. The machine integrates a horizontal drum (40 swinging blades) to cut standing gorse and initiate comminution, followed by an auger and a turbine that propel the shredded biomass through a duct into a suspended container mounted on the tractor’s front three-point hitch. Cutting was performed above ground level to reduce soil contamination, and loads were tipped at the plot edge. The container volume was 5 m³. The transport distance was very short (about 200 m), so the focus was placed on harvesting performance rather than long-distance logistics.
The two stands differed markedly in structure and biomass availability. Mean gorse height was 157 cm in Ruente and 252 cm in Cruz de Sopeña, while canopy cover fraction was 66.5% and 92.5%, respectively. These differences translated into contrasting harvesting outputs. Ruente delivered 12,129 kg of fresh biomass and 4,924 kg of dry biomass over 287 minutes of productive harvesting time, across 9,800 m² treated, corresponding to 5.02 t dry matter per hectare. Cruz de Sopeña produced 31,814 kg fresh and 13,966 kg dry biomass over 501 minutes, across 6,700 m² treated, equivalent to 20.85 t dry matter per hectare.
Productivity in mass terms reached 1.03 tDM per productive machine hour (PMH) in Ruente and 1.67 tDM per PMH in Cruz de Sopeña. Area productivity was 0.20 ha per PMH in Ruente and 0.08 ha per PMH in Cruz de Sopeña, reflecting the heavier, denser vegetation and the associated reduction in forward speed in the high-biomass site. Harvesting efficiency, defined as harvested biomass divided by estimated standing biomass before treatment, was 57.43% in Ruente and 70.27% in Cruz de Sopeña. The uncollected fraction measured after harvesting was 3.72 tDM/ha in Ruente and 8.82 tDM/ha in Cruz de Sopeña, representing 42.6% and 29.7% of the total biomass involved (harvested plus uncollected), respectively.
Using an hourly machine cost of 100 € per productive machine hour, unit costs were 97.14 €/tDM and 488.10 €/ha in Ruente, and 59.79 €/tDM and 1,246.27 €/ha in Cruz de Sopeña. The denser stand reduced the cost per tonne through higher throughput, even though the cost per hectare increased due to the larger biomass stock treated. Overall, results show that the same harvesting concept can deliver substantially different performance depending on shrub height, cover and site roughness, and they highlight the importance of matching machine settings and operational strategy to stand structure when targeting efficient gorse biomass extraction at short transport distances. New demonstrations will be carried out within the BIOTER-LAB project in 2026 and 2027.
| Keywords | Ulex; biomass; harvester; shrubland |
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